Thanks for the reply Marc ! If I place my pass before ccp then I guess I have to implement the means to perform calculations on my own so that it can duplicate the functionality of ccp, right? I will also look at the source code to see if I can modify the source code directly. Is pass_ccp in tree-ssa-ccp.c the correct one to look at? Please let me know. Yes, I have tried the second option you suggested. It's not convenient for my purpose. Thanks and regards, Sandeep. On Sun, Jan 5, 2014 at 10:24 PM, Marc Glisse <marc.glisse@xxxxxxxx> wrote: > On Sun, 5 Jan 2014, Sandeep K Chaudhary wrote: > >> Hi guys, >> >> I want to write a pass which can find the calculations performed on >> the right hand side of each statement. In the below example - >> >> VAR1 = 1; >> VAR1++; >> VAR1 = VAR1 + 5; >> >> I want to be able to capture the equivalent statements i.e. >> >> VAR1 = 1; >> VAR1 = 2; >> VAR1 = 7; >> >> To achieve this, I dumped various intermediate files using >> "-fdump-tree-all'. I looked at all of them manually and found that >> either the statements are non-evaluated (during initial stages) or >> they are completely optimized, hence losing the intermediate >> assignment calculations (during later stages). There is no pass which >> generates dumps related to the intermediate assignment calculations. >> >> I am not able to understand where I should aim to place my pass in >> order to achieve the above mentioned functionality. Initially, I had >> thought of writing IPA pass but I looked at 'copyprop' and 'forwprop' >> dumps and saw that everything is optimized to the last statement. I am >> not able to understand how a pass should be placed between GIMPLE >> stage and later stages so that intermediate calculations such as the >> ones mentioned above in the example, can be captured. Please provide >> suggestions and help regarding this. > > > Short answer: you can't. > > You can either have your passe before ccp, and duplicate the functionality > of ccp, or you can hack the ccp pass to insert your code in it, but I doubt > there is a suitable plugin hook for that, so you may have to edit gcc's > source code directly. > > If you compile with -g and look at debug statements, the information is not > completely lost after the pass that optimizes this to just VAR1 = 7, but it > still wouldn't be convenient to use that for your purpose. > > -- > Marc Glisse -- Thanks and regards, Sandeep K Chaudhary.
